U.S. patent application number 10/717327 was filed with the patent office on 2004-11-18 for control apparatus for controlling regenerative operation of vehicle motor.
This patent application is currently assigned to Honda Motor Co., Ltd.. Invention is credited to Anekawa, Akihiro, Kato, Shinji, Tamenori, Koji, Yamamoto, Koichi.
Application Number | 20040227480 10/717327 |
Document ID | / |
Family ID | 32700456 |
Filed Date | 2004-11-18 |
United States Patent
Application |
20040227480 |
Kind Code |
A1 |
Kato, Shinji ; et
al. |
November 18, 2004 |
Control apparatus for controlling regenerative operation of vehicle
motor
Abstract
A control apparatus for controlling a regenerative operation of
a vehicle motor includes a vehicle motor as a drive source of a
vehicle, an energy storage device, including plural cells, for
storing regenerative energy generated by a regenerative operation
of the vehicle motor, and a total voltage measuring device for
measuring a total voltage that is a sum of inter-terminal voltages
of the plural cells, a cell voltage judgment device for determining
whether the inter-terminal voltage of any one of the plural cells
exceeds a predetermined regeneration limitation voltage, a total
voltage estimating device for determining, when it is determined by
the cell voltage judgment device that the inter-terminal voltage of
any one of the cells exceeds the predetermined regeneration
limitation voltage, an estimated total voltage which is defined as
a total voltage at a time when the inter-terminal voltage of the
one of the cells reaches a regeneration prohibition voltage that is
higher than the predetermined regenerative operation limiting
voltage, and a control device for setting an amount of regeneration
depending on a difference between the estimated total voltage
determined by the total voltage estimating device and the total
voltage measured by the total voltage measuring device.
Inventors: |
Kato, Shinji;
(Utsunomiya-shi, JP) ; Yamamoto, Koichi;
(Utsunomiya-shi, JP) ; Tamenori, Koji;
(Utsunomiya-shi, JP) ; Anekawa, Akihiro;
(Utsunomiya-shi, JP) |
Correspondence
Address: |
LAHIVE & COCKFIELD, LLP.
28 STATE STREET
BOSTON
MA
02109
US
|
Assignee: |
Honda Motor Co., Ltd.
Tokyo
JP
|
Family ID: |
32700456 |
Appl. No.: |
10/717327 |
Filed: |
November 18, 2003 |
Current U.S.
Class: |
318/376 ;
318/139 |
Current CPC
Class: |
Y02T 10/64 20130101;
B60L 58/15 20190201; H02P 3/14 20130101; Y02T 10/70 20130101 |
Class at
Publication: |
318/376 ;
318/139 |
International
Class: |
H02P 003/14 |
Foreign Application Data
Date |
Code |
Application Number |
Nov 20, 2002 |
JP |
2002-336688 |
Claims
1. A control apparatus for controlling a regenerative operation of
a vehicle motor comprising: a vehicle motor as a drive source of a
vehicle; an energy storage device, including plural cells that are
connected to each other in series, for storing regenerative energy
generated by a regenerative operation of the vehicle motor; a total
voltage measuring device for measuring a total voltage that is a
sum of inter-terminal voltages of the plural cells; a cell voltage
judgment device for determining whether the inter-terminal voltage
of any one of the plural cells exceeds a predetermined regeneration
limitation voltage; a total voltage estimating device for
determining, when it is determined by the cell voltage judgment
device that the inter-terminal voltage of any one of the cells
exceeds the predetermined regeneration limitation voltage, an
estimated total voltage which is defined as a total voltage at a
time when the inter-terminal voltage of the ones of the cells
reaches a regeneration prohibition voltage that is higher than the
predetermined regenerative operation limiting voltage; and a
control device for setting an amount of regeneration depending on a
difference between the estimated total voltage determined by the
total voltage estimating device and the total voltage measured by
the total voltage measuring device.
2. A control apparatus for controlling regenerative operation of
vehicle motor according to claim 1, comprising a regeneration
prohibiting device for not allowing the vehicle motor to perform a
regenerative operation when the inter-terminal voltage of any one
of the cells reaches the regeneration prohibition voltage before
the total voltage measured by the total voltage measuring device
reaches the estimated total voltage determined by the total voltage
estimating device.
3. A control apparatus for controlling regenerative operation of
vehicle motor according to claim 1, wherein the [regeneration]
control device sets a greater amount of regeneration when the
difference between the estimated total voltage determined by the
total voltage estimating device and the total voltage measured by
the total voltage measuring device is greater.
Description
[0001] Priority is claimed on Japanese Patent Application No.
2002-336688, filed Nov. 20, 2002, the content of which is
incorporated herein by reference.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The present invention relates to a control apparatus for
controlling a regenerative operation of a vehicle motor.
[0004] 2. Description of Related Art
[0005] Conventionally, a charging apparatus for a battery assembly
(battery) which is formed by connecting plural cell units of
secondary batteries or the like to each other in series is known,
in which the charging apparatus includes cell voltage measuring
circuits and bypass circuits each being connected to each of the
cell units, the charging apparatus determines whether each of the
unit cells is in a fully charged state depending on an
inter-terminal voltage measured by each of the cell voltage
measuring circuits, makes charging current for any of the cell
units which are determined to be fully charged to flow to the
bypass circuits so that the inter-terminal voltages of the cell
units are equalized with each other, and in addition, sets charging
current for each of the cell units depending on the measured
inter-terminal voltage (see, for example, Japanese Unexamined
Patent Application, First Publication No. H04-299032).
[0006] Moreover, a type of vehicle is known in which the
above-mentioned type of battery is installed as a driving power
source, a driving motor is operated by supplying electrical power
thereto from the battery, regenerated energy generated through a
regenerative operation of the driving motor during a deceleration
operation or the like of the vehicle is stored in the battery, and
electrical energy is transmitted between the battery and the
driving motor.
[0007] In the charging apparatus for a battery as an example of
conventional technical measures, when it is determined that one of
the cells is in a fully charged state, charging current to the
specific cell is reduced to zero or to a level of self-discharging
current. Accordingly, in the case in which the above-mentioned type
of charging apparatus is installed in a vehicle, when it is
determined that one of the cells is in a fully charged state when
regenerated energy generated through a regenerative operation of
the driving motor during a deceleration operation or the like of
the vehicle is charged into the battery, the amount of regeneration
by the driving motor is reduced to a level of zero or substantially
zero. As a result, a rapid change in the deceleration operation of
the vehicle, which is not expected by the driver, may occur, and
thereby the driver may feel unusual sensations in the vehicle
behavior.
SUMMARY OF THE INVENTION
[0008] The present invention was conceived in view of the above
circumstances, and an object thereof is to provide a control
apparatus for controlling a regenerative operation of a vehicle
motor which enables smooth running of a vehicle using the vehicle
motor while protecting an energy storing device that sends and
receives electrical energy to and from the vehicle motor.
[0009] In order to achieve the above object, the present invention
provides a control apparatus for controlling a regenerative
operation of a vehicle motor including: a vehicle motor as a drive
source of a vehicle; an energy storage device, including plural
cells that are connected to each other in series, for storing
regenerative energy generated by a regenerative operation of the
vehicle motor; a total voltage measuring device for measuring a
total voltage that is a sum of inter-terminal voltages of the
plural cells; a cell voltage judgment device for determining
whether the inter-terminal voltage of any one of the plural cells
exceeds a predetermined regeneration limitation voltage; a total
voltage estimating device for determining, when it is determined by
the cell voltage judgment device that the inter-terminal voltage of
any one of the cells exceeds the predetermined regeneration
limitation voltage, an estimated total voltage which is defined as
a total voltage at a time when the inter-terminal voltage of the
one of the cells reaches a regeneration prohibition voltage that is
higher than the predetermined regenerative operation limiting
voltage; and a control device for setting an amount of regeneration
depending on a difference between the estimated total voltage
determined by the total voltage estimating device and the total
voltage measured by the total voltage measuring device.
[0010] According to the above control apparatus for controlling a
regenerative operation of a vehicle motor, when it is determined
that the inter-terminal voltage of any one of the cells exceeds the
predetermined regeneration limitation voltage, the total voltage
estimating device estimates the total voltage (an estimated total
voltage) which is defined as the voltage at a time when the
inter-terminal voltages of the cells whose inter-terminal voltages
have exceeded the regeneration limitation voltage reach a
regeneration prohibition voltage by, for example, adding a value,
which is obtained by summing up the differences between the
regeneration limitation voltage and the regeneration prohibition
voltage over the plural cells, to the total voltage at the time
measured by the total voltage measuring device. The control device
sets an amount of regeneration by the vehicle motor depending on
the difference between the estimated total voltage and the measured
total voltage, such that, for example, the less the difference, the
lower the amount of regeneration is set, and the greater the
difference, the higher the amount of regeneration is set.
[0011] As a result, the amount of regeneration can be smoothly
reduced when compared with the cases in which the amount of
regeneration is reduced to a predetermined value including zero in
a stepped manner for preventing overcharging of the cells when, for
example, the inter-terminal voltage of any one of the cells reaches
the regeneration prohibition voltage, or when, for example, the
measured total voltage reaches a predetermined upper limit, and
thus excessive and rapid changes in driving states can be
prevented.
[0012] The above control apparatus for controlling regenerative
operation of a vehicle motor may further include a regeneration
prohibiting device for not allowing the vehicle motor to perform a
regenerative operation when the inter-terminal voltage of any one
of the cells reaches the regeneration prohibition voltage before
the total voltage measured by the total voltage measuring device
reaches the estimated total voltage determined by the total voltage
estimating device.
[0013] According to the above control apparatus for controlling a
regenerative operation of a vehicle motor, even when, for example,
any one of the cell voltages reaches the regeneration prohibition
voltage before the measured total voltage reaches the estimated
total voltage, i.e., even when the estimated total voltage includes
an error, overcharging of the cells can be reliably prevented by
prohibiting or restraining the regenerative operation of the
vehicle motor by the regeneration prohibiting device.
[0014] Moreover, in this case, even when, for example, the amount
of regeneration is reduced to a predetermined value including zero
in a stepped manner at a time at which the cell voltage reaches the
regeneration prohibition voltage, the amount of regeneration is
merely changed to a predetermined value from a value which is
obtained by being appropriately reduced depending on the difference
between the estimated total voltage and the measured total voltage;
therefore, changes in the amount of regeneration can be reduced
when compared with the case in which, for example, the amount of
regeneration is reduced to a predetermined value in a stepped
manner without executing such a reduction operation depending on
the difference between the estimated total voltage and the measured
total voltage, and thus excessive changes in driving states can be
prevented.
BRIEF DESCRIPTION OF THE DRAWINGS
[0015] FIG. 1 is a schematic constitution diagram showing an
embodiment of the control apparatus for controlling a regenerative
operation of a vehicle motor according to the present
invention.
[0016] FIG. 2 is a flowchart showing operations of the control
apparatus for controlling a regenerative operation of a vehicle
motor shown in FIG. 1.
[0017] FIG. 3A is a diagram showing an example of time-domain
changes in total voltage, FIG. 3B is a diagram showing an example
of time-domain changes in cell voltage, and FIG. 3C is a diagram
showing an example of time-domain changes in an amount of
regeneration.
[0018] FIG. 4 is a graph showing an example of changes in the
amount of regeneration depending on the difference between an
estimated total voltage and a measured total voltage.
DETAILED DESCRIPTION OF THE INVENTION
[0019] An embodiment of the control apparatus for controlling a
regenerative operation of a vehicle motor according to the present
invention will be explained below with reference to appended
drawings.
[0020] A regenerative operation control apparatus 10 for a vehicle
motor according to the present embodiment is installed, for
example, in a fuel cell powered vehicle, a hybrid vehicle, or the
like, and as shown, for example, in FIG. 1, in the case in which a
fuel cell powered vehicle includes a fuel cell 11, a current and
voltage controller 12, a capacitor 13, an output controller 14, a
driving motor 15, a protection device 16, and a control device 17,
the regenerative operation control apparatus 10 includes, for
example, the output controller 14, the protection device 16, the
control device 17, a current sensor 21, a voltage sensor 22, and a
capacitor temperature sensor 23.
[0021] The fuel cell 11 is formed by stacking a number of fuel cell
units, each of which is formed by sandwiching an electrolyte
electrode assembly by a pair of separators, the electrolyte
electrode assembly being formed by sandwiching a solid polymer
electrolyte membrane by a fuel electrode (an anode) including an
anode catalyst and a gas diffusion layer and an oxygen electrode (a
cathode) including a cathode catalyst and a gas diffusion
layer.
[0022] When a fuel gas (a reaction gas) including hydrogen is
supplied to the anode of the fuel cell 11 from a high pressure
hydrogen tank, hydrogen is ionized through a catalytic reaction on
the anode catalyst of the anode, ionized hydrogen moves to the
cathode via the solid polymer electrolyte membrane that is
appropriately humidified, and electrons generated during the
movement are supplied to an external circuit and used as direct
current electrical energy. For example, air, which is an oxidizing
gas (a reaction gas) including oxygen, is supplied to the cathode
by an air compressor, and hydrogen ions, electrons, and oxygen
react at the cathode to generate water.
[0023] Generated electrical current extracted from the fuel cell 11
is input to the current and voltage controller 12 to which the
capacitor 13, which acts as an energy storing device, and which
includes electric dual-layer capacitors, electrolytic capacitors,
or the like, is connected.
[0024] The fuel cell 11 and the capacitor 13 are connected in
parallel with the driving motor 15, which acts as an electrical
load, via the output controller 14.
[0025] The current and voltage controller 12 includes, for example,
a DC-DC chopper, and controls current value of the generated
electrical current output from the fuel cell 11 according to a
current command output from the control device 17, i.e., a power
generation command sent to the fuel cell 11.
[0026] The output controller 14 includes, for example, a PWM
inverter executing pulse width modulation, and controls a driving
operation and a regenerative operation of the driving motor 15
according to a control command output from the control device 17.
For example, when the driving motor 15 is used for a driving
operation, direct electrical power output from the current and
voltage controller 12 and the capacitor 13 is converted into
three-phase alternating current and supplied to the driving motor
15 according to a torque command output from the control device 17.
On the other hand, when the driving motor 15 is used for a
regenerative operation, three-phase alternating current output from
the driving motor 15 is converted into direct current, and the
capacitor is charged therewith.
[0027] The driving motor 15, which is, for example, a permanent
magnet type three-phase synchronous motor in which permanent
magnets are used for forming a magnetic field, is driven and
controlled by three-phase alternating current supplied from output
controller 14, and the driving motor 15 also acts as a generator so
as to generate regenerative braking force and so that the kinetic
energy of the vehicle is recovered as electrical energy when
driving force is transmitted to the driving motor 15 from driving
wheels during a deceleration operation of the vehicle.
[0028] The capacitor 13 is formed, for example, by connecting
plural capacitor cells to each other in series, each of which
includes an electric dual-layer capacitor, an electrolytic
capacitor, or the like, and the protection device 16 is connected
to the capacitor 13 via voltage measuring lines which are connected
to input and output terminals of the capacitor cells,
respectively.
[0029] The protection device 16 includes, for example, a cell
voltage measuring circuit for measuring inter-terminal voltage
(cell voltage) of each of the capacitor cells, a bypass circuit for
allowing charging current supplied to each of the capacitor cells
to be discharged by bypassing the same, a bypass control unit, and
a cell voltage judgment unit. The cell voltage measuring circuit
and the bypass circuit are connected to each of the capacitor cells
via the voltage measuring lines.
[0030] The bypass circuit includes, for example, bypass resistors
and switching elements for switching ON and OFF states of the
electrical current to be supplied to the bypass resistors.
[0031] The bypass control unit controls switching of ON and OFF
operations of the switching elements in the bypass circuit, and
outputs an ON signal corresponding to a logical high level which
places the switching elements in the ON state according to the
control command output from the control device 17, or according to
a determination result indicating that the cell voltage of the
capacitor cell exceeds a predetermined regeneration limitation
voltage VR (e.g., VR=2.5 V). As a result, the corresponding
capacitor cell discharges via the bypass resistors, and charging
current to be supplied to the capacitor cell is made to bypass via
the bypass resistors.
[0032] The cell voltage judgment unit determines whether voltage of
each of the cells exceeds the predetermined regeneration limitation
voltage VR (e.g., VR=2.5 V), or a regeneration prohibition voltage
VU (e.g., VU=2.7 V) which is higher than the regeneration
limitation voltage, and sends the determination result to the
bypass control unit and the control device 17.
[0033] According to, for example, an operation state of the
vehicle, the hydrogen concentration of the reaction gas supplied to
the anode of the fuel cell 11, the hydrogen concentration of a
discharged gas discharged from the anode of the fuel cell 11, a
power generation state of the fuel cell 11, e.g., output voltage of
each of the fuel cell units or generated current output from the
fuel cell 11, or the like, the control device 17 outputs commands
for determining the flow rates of the reaction gases supplied from
the air compressor and the hydrogen tank to the fuel cell 11 so as
to control the power generation state of the fuel cell 11, and
sends a power generation command for the fuel cell 11 to the
current and voltage controller 12 so as to control the current
value of the generated electrical current output from the fuel cell
11.
[0034] Moreover, the control device 17 controls an electrical power
conversion operation of the PWM inverter which is provided in the
output controller 14, and, when, for example, the driving motor 15
is used for a driving operation, the control device 17 calculates a
torque command according to an accelerator opening signal
corresponding to the amount of depression of the accelerator pedal
operated by the driver. When the torque command is input to the
output controller 14 by the control device 17, pulse width
modulated signals corresponding to the torque command are input to
the PWM inverter, and phase currents for producing required torque
are sent to the phases of the driving motor 15, respectively.
[0035] In order to achieve such a control operation, the control
device 17 is provided with, for example, a measured signal output
from the current sensor 21 for measuring the current value of the
generated electrical current output from the fuel cell 11, a
measured signal output from an accelerator opening sensor 31, a
signal output from a brake switch 32 for detecting a brake
operation by the driver, and a signal output from an IG switch 33
for indicating the operation of the vehicle.
[0036] Furthermore, the control device 17 controls the regenerative
operation of the driving motor 15 according to the determination
result output from the cell voltage judgment unit of the protection
device 16, i.e., the determination result as to whether or not the
voltage of each of the cells exceeds a criterion such as the
predetermined regeneration limitation voltage VR or the
regeneration prohibition voltage VU, and the state of the capacitor
13, e.g., the temperature of the capacitor 13 or a measured total
voltage (a measured total voltage SVE) which is obtained by summing
up the cell voltages of the plural capacitor cells.
[0037] As explained in detail below, when, for example, it is
determined that the cell voltage of any one of the capacitor cells
exceeds the predetermined regeneration limitation voltage VR, the
control device 17 estimates a total voltage (i.e., an estimated
upper limit of total voltage SVU) at a time at which the cell
voltage of the specific cell reaches the regeneration prohibition
voltage VU. The control device 17 controls the regenerative
operation of the driving motor 15 depending on the difference
between the estimated upper limit of total voltage SVU and the
measured total voltage SVE over the period until the cell voltage
of any one of the capacitor cells reaches the regeneration
prohibition voltage VU. For example, the control device 17 sets a
lower amount of regeneration as the difference decreases, and sets
a higher amount of regeneration as the difference increases.
[0038] In order to achieve such a control operation, the control
device 17 is connected in parallel with the capacitor 13, and is
provided with a measured signal output from the voltage sensor 22
for measuring the total voltage which is obtained by summing up the
cell voltages of the capacitor cells, and a measured signal output
from the capacitor temperature sensor 23 for measuring the
temperature of the capacitor 13.
[0039] The regenerative operation control apparatus 10 for a
vehicle motor according to the present embodiment is constructed as
explained above. Next, the operation of the regenerative operation
control apparatus 10, in particular, the control operation for
controlling the amount of regeneration (e.g., the current value of
the regenerated current output from the output controller 14) will
be explained with reference to the appended drawings.
[0040] First, for example, in step S01, the cell voltage of each of
the capacitor cells of the capacitor 13 is measured.
[0041] Next, in step S02, it is determined whether any one of the
cell voltages exceeds the predetermined regeneration limitation
voltage VR (e.g., VR=2.5 V).
[0042] When the result of the determination is "YES", the operation
proceeds to step S05 which will be explained below.
[0043] In contrast, when the result of the determination is "NO",
the operation proceeds to step S03.
[0044] In step S03, the flag value of a flag F, which indicates
that the estimated upper limit of total voltage SVU is estimated
after any one of the cell voltages exceeds the predetermined
regeneration limitation voltage VR, is set to be zero, i.e., the
flag F is reset. The flag F is provided for preventing duplicated
estimation of the estimated upper limit of total voltage SVU, and
when the flag value is "1", the estimated upper limit of total
voltage SVU is not allowed to be estimated.
[0045] In step S04, the amount of regeneration is not restrained,
the driving motor 15 is allowed to perform the regenerative
operation, and the series of the operations is terminated.
[0046] In step S05, as a bypass operation, the switching elements
of the bypass circuit which are connected in parallel with the
capacitor cells are placed in the ON state so as to make the
capacitor cells discharge via the bypass resistors while the
charging current to be supplied to the capacitor cells is bypassed
to the bypass resistors.
[0047] Next, in step S06, it is determined whether any one of the
cell voltages exceeds the predetermined regeneration prohibition
voltage VU (e.g., VU=2.7 V) which is greater than the regeneration
limitation voltage VR.
[0048] When the result of the determination is "YES", the operation
proceeds to step S11 which will be explained below.
[0049] In contrast, when the result of the determination is "NO",
the operation proceeds to step S03.
[0050] In step S07, it is determined whether the flag value of the
flag F is zero.
[0051] When the result of the determination is "NO", the operation
proceeds to step S10 which will be explained below.
[0052] In contrast, when the result of the determination is "YES",
the operation proceeds to step S08.
[0053] In step S08, the total voltage (i.e., the estimated upper
limit of total voltage SVU) at a time at which the cell voltage of
the specific cell which exceeds the predetermined regeneration
limitation voltage VR reaches the regeneration prohibition voltage
VU is estimated.
[0054] For example, in this case, a value, which is obtained by
adding a total value obtained by multiplying the difference between
the regeneration prohibition voltage VU and the regeneration
limitation voltage VR by the number N of the capacitor cells
((VU-VR).times.N) to the total voltage of the capacitor 13 measured
at the time (the measured total voltage SVE), is set to be the
estimated upper limit of total voltage SVU.
[0055] In step S09, the flag value of the flag F, which indicates
that the estimated upper limit of total voltage SVU is estimated
after any one of the cell voltages exceeds the predetermined
regeneration limitation voltage VR, is set to be "1".
[0056] In step S10, the amount of regeneration is set by retrieving
a value from, for example, a predetermined regeneration amount
table shown in FIG. 4 depending on the difference between the
measured total voltage SVE of the capacitor 13 at the time and the
estimated upper limit of total voltage SVU, the driving motor 15 is
controlled so as to perform a regenerative operation depending on
the amount of regeneration, and then the series of the operations
is terminated.
[0057] The predetermined regeneration amount table used in step S10
is defined such that restriction of regeneration is cancelled when
the difference between the measured total voltage SVE and the
estimated total voltage SVU is greater than or equal to a
predetermined difference #V, and the degree of restriction is
reduced as the difference increases, i.e., the amount of
regeneration is increased from 0% to 100% as the difference
increases, where the amount of regeneration (e.g., current value of
regenerated electrical current) defined to be 100% when no
restriction is applied to regeneration.
[0058] In step S11, the regenerative operation of the driving motor
15 is not allowed, i.e., the amount of regeneration is set to be
0%, and the series of the operations is terminated.
[0059] As shown, for example, in FIGS. 3A to 3C, before time t1,
i.e., when the cell voltages are below the regeneration limitation
voltage VR (e.g., VR=2.5V), the estimated upper limit of total
voltage SVU is set to be a predetermined upper limit U0, and the
amount of regeneration is set to be 0%.
[0060] When it is determined at time t1 that any one of the cell
voltages (e.g., the maximum cell voltage shown in FIG. 3B) exceeds
the regeneration limitation voltage VR, the bypass operation is
executed, and the estimated upper limit of total voltage SVU is set
to be U1 (U1=SVE+(VU-VR).times.N) which is obtained by adding a
total value obtained by multiplying the difference between the
regeneration prohibition voltage VU and the regeneration limitation
voltage VR by the number N of the capacitor cells to the measured
total voltage SVE.
[0061] When any one of the cell voltages exceeds the regeneration
limitation voltage VR, and the difference between the measured
total voltage SVE and the estimated upper limit of total voltage
SVU changes so as to decrease, i.e., during a period from time t1
to time t2, the amount of regeneration is reduced from 100% to 0%
according to the predetermined regeneration amount table.
[0062] When the difference between the measured total voltage SVE
and the estimated upper limit of total voltage SVU is zero, i.e.,
during a period from time t2 to time t3, the amount of regeneration
is set to be 0%, and the regenerative operation of the driving
motor 15 is not allowed.
[0063] When the difference between the measured total voltage SVE
and the estimated upper limit of total voltage SVU changes so as to
increase, i.e., during a period from time t3 to time t4, the amount
of regeneration is increased from 0% to 100%, and when it is
determined at time t4 that the cell voltages are below a value
obtained by subtracting a predetermined relief hysteresis from the
regeneration limitation voltage VR, the estimated upper limit of
total voltage SVU is again set to be U0 (.gtoreq.U1).
[0064] When it is determined at time t5 that any one of the cell
voltages exceeds the regeneration limitation voltage VR, the bypass
operation is executed, and the estimated upper limit of total
voltage SVU is set to be U1 (U1=SVE+(VU-VR).times.N), and when the
difference between the measured total voltage SVE and the estimated
upper limit of total voltage SVU changes so as to decrease, i.e.,
during a period from time t5 to time t6, the amount of regeneration
is reduced from 100% to 0% according to the predetermined
regeneration amount table.
[0065] When it is determined at time t6 that any one of the cell
voltages exceeds the regeneration prohibition voltage VU (e.g.,
VU=2.7 V), the amount of regeneration is set to be 0% even when,
for example, the amount of regeneration obtained from the
regeneration amount table is greater than 0% so that the
regenerative operation of the driving motor 15 is not allowed. As
shown, for example, in FIG. 3A, the estimated upper limit of total
voltage SVU is set to be the measured total voltage SVE, i.e., the
difference between the measured total voltage SVE and the estimated
upper limit of total voltage SVU is set to be zero.
[0066] When it is determined at time t8 that any one of the cell
voltages exceeds the regeneration limitation voltage VR, and the
cell voltages are below a value obtained by subtracting a
predetermined relief hysteresis from the regeneration prohibition
voltage VU, the estimated upper limit of total voltage SVU is again
set to be U1 (U1=SVE+(VU-VR).times.N), and a setting in which the
difference between the measured total voltage SVE and the estimated
upper limit of total voltage SVU is set to be zero is cancelled.
Accordingly, a setting in which the amount of regeneration is set
to be 0% is cancelled, and the regenerative operation of the
driving motor 15 is performed according to the amount of
regeneration obtained from the regeneration amount table.
[0067] When the difference between the measured total voltage SVE
and the estimated upper limit of total voltage SVU changes so as to
increase, i.e., during a period from time t8 to time t9, the amount
of regeneration is increased to 100% according to the predetermined
regeneration amount table, and when it is determined at time t9
that the cell voltages are below a value obtained by subtracting a
predetermined relief hysteresis from the regeneration limitation
voltage VR, the estimated upper limit of total voltage SVU is again
set to be U0 (>U1).
[0068] As explained above, according to the regenerative operation
control apparatus 10 for a vehicle motor, the amount of
regeneration can be smoothly changed by controlling the amount of
regeneration of the driving motor 15 depending on the difference
between the estimated upper limit of total voltage SVU, which is
determined when any one of the cell voltages exceeds the
regeneration limitation voltage VR, and the measured total voltage
SVE, and thus excessive and rapid changes in driving states can be
prevented.
[0069] Moreover, overcharging of the capacitor 13 can be prevented
by not allowing the driving motor 15 to perform a regenerative
operation when any one of the cell voltages exceeds the
predetermined regeneration prohibition voltage VU which is greater
than the regeneration limitation voltage VR even when the amount of
regeneration is controlled depending on the difference between the
estimated upper limit of total voltage SVU and the measured total
voltage SVE.
[0070] In addition, because the regeneration limitation voltage VR
is also used as a criterion for determining as to whether the
bypass operation should be executed, the structure of the
regenerative operation control apparatus 10 for a vehicle motor,
which is configured so as to execute the bypass operation and the
regenerative control operation, can be simplified.
[0071] In the above-described embodiment, the amount of
regeneration is set according to the predetermined regeneration
amount table depending on the difference between the measured total
voltage SVE and the estimated upper limit of total voltage SVU. In
the case in which, for example, the regenerated current is
controlled so as to control the amount of regeneration, a current
measuring device (not shown) is provided for measuring electrical
current at the capacitor 13, and the control device 17, first,
estimates an open-terminal voltage, i.e., voltage with no current,
of the capacitor 13 based on the measured total voltage SVE
measured by the voltage sensor 22, an internal resistance of the
capacitor 13, and measured current. The control device 17, then,
calculates a regenerative electrical power required for making the
estimated open-terminal voltage to reach the estimated upper limit
of total voltage SVU, and executes a feedback control operation
with respect to electrical current (i.e., regenerated current)
depending on the calculated regenerative electrical power.
[0072] In the above-described embodiment, the regenerative
operation of the driving motor 15 is not allowed in step S11;
however, the invention is not limited to this, and the amount of
regeneration of the driving motor 15 may be, for example, reduced
to substantially a level of zero.
[0073] In the above-described embodiment, the amount of
regeneration is controlled depending on the difference between the
estimated upper limit of total voltage SVU and the measured total
voltage SVE after any one of the cell voltages exceeds the
predetermined regeneration limitation voltage VR; however, in
addition, a table of the estimated upper limit of total voltage SVU
in which the estimated upper limit of total voltage SVU varies
depending on the temperature of the capacitor 13 may be provided,
and the amount of regeneration may be controlled depending on the
difference between the measured total voltage SVE and a smaller
value which is obtained by comparing the estimated upper limit of
total voltage SVU estimated depending on the cell voltage with the
estimated upper limit of total voltage SVU retrieved depending on
the temperature of the capacitor 13.
[0074] In the above-described embodiment, the energy storage device
which sends and receives electrical energy to and from the driving
motor 15 is the capacitor 13; however, the invention is not limited
to this, and the energy storage device may be, for example, a
battery assembly formed by connecting plural cells to each other in
series, each of which includes a secondary battery such as a
lithium ion battery.
[0075] Advantageous Effects Obtainable by the Invention
[0076] As explained above, according to the control apparatus for
controlling a regenerative operation of a vehicle motor of the
present invention, the amount of regeneration can be smoothly
reduced, and thus excessive and rapid changes in driving states can
be prevented.
[0077] Moreover, according to another control apparatus for
controlling a regenerative operation of a vehicle motor of the
present invention, excessive changes in driving states can be
prevented while reliably preventing overcharging of the cells.
* * * * *